Remote-control flying vehicles are becoming increasingly more popular and sophisticated. While larger craft such as military and civilian drone aircraft have been in use for only the last two decades, smaller radio-controlled flying vehicles built and flown by hobbyists have been around for much longer. Generally, remote-control flying vehicles are either fixed wing, like a plane, or hovering, like a helicopter or quadcopter.
One example of a smaller, hovering type craft is described in U.S. Pat. No. 7,931,239, entitled “Homeostatic Flying Hovercraft,” which teaches the use of a homeostatic hover control system in combination with a hand-held controller to cause the craft to mimic the orientation of the controller in terms of yaw, pitch, roll, and lateral flight maneuvers. Another example of a quadcopter is the Parrot AR Drone that utilizes a Wi-Fi connection between the quadcopter and a smart phone or tablet that serves as a tilt-based remote control. Still another example is the Walkera QR Lady Bird brand mini-quadcopter that is controlled via a conventional dual joystick remote control. These kinds of electronically stabilized hovercraft or quadcopter designs with three or more separate rotors are generally more stable and easier to learn to fly than the single shaft, dual counter-rotating rotor, model helicopters that may use some form of mechanical gyro stabilization. And, like the Lady Bird mini-quadcopter, these less-expensive single-shaft, dual counter-rotating rotor, model helicopters are typically controlled via a conventional dual joystick remote control.
A problem with current designs for these kinds of smaller, hovering remote-control flying craft is that the competing design considerations of weight, cost and performance have resulted in a very limited set of designs for how these craft are constructed. The design of the single-shaft model helicopters has the dual counter-rotating rotors on the top of the craft where they are exposed to obstacles both above and to the sides of the rotors. Running the rotors into an obstacle, like a ceiling when flying indoors, almost always causes the craft to crash and potentially suffer damage as a result. The design of most quadcopters utilizes a cross configuration formed of very stiff, carbon-fiber rods that hold the motors away from the center of the craft. Stiff carbon-fiber rods are used to minimize the torsion and vibration that occurs in a quadcopter design when the motors are not mounted in the center of gravity of the craft as is done in a single-shaft, counter-rotating helicopter design.
These existing designs for smaller, hovering remote-control flying craft suffer from various problems, including cost of manufacture, ease of operation, accuracy of navigation, durability, and safety during operation, among others problems. There is a need for an inexpensive, yet robust design for a smaller, hovering remote-control flying craft.